Paul's performance in South Carolina underscored the limitations of his message with Republican voters, who share many of Paul's views on cutting taxes and spending but have yet to embrace his largely isolationist foreign policy positions. He came under fire in a debate this week from GOP rivals when he questioned the U.S. mission that killed Osama bin Laden.

Paul's performance in South Carolina underscored the limitations of his message with Republican voters, who share many of Paul's views on cutting taxes and spending but have yet to embrace his largely isolationist foreign policy positions. He came under fire in a debate this week from GOP rivals when he questioned the U.S. mission that killed Osama bin Laden.